Back in 1971, when an acquaintance showed up at his office to ask him to lead a committee on the future of downtown Portland, Gisvold was a 31-year-old real-estate lawyer and a Grade-A do-gooder, not an expert on cities.

He and his family lived in a big house in the Irvington neighborhood, then a gritty place where he spent many a cocktail party trying to convince other young professionals that Northeast Portland wasn't as scary as they'd heard. He rode a bicycle to work, though friends thought he was crazy, and officials at his large downtown office building responded to his request for bike racks with a single, lonely stall. He'd done some neighborhood activism and found the work fulfilling, so when an architect in town asked for help with downtown, Gisvold agreed without much thought.

"It seemed like fun," he said, "and not that much work."

It turned out to be a great deal of work, more than a year of practically full-time effort. But the document Gisvold and his committee helped planners produce became the 1972 Downtown Plan, the blueprint for the vital urban core Oregonians enjoy today and a nationally renowned bit of advanced thinking about what the modern U.S. city can be: Walkable. Livable. Alive.

"I know there were people back then who said, 'What the hell are these people thinking?'" said Chet Orloff, a historian and Portland State University professor. "Everywhere you looked, in every city, people were fleeing and cities were talking about how to make driving easier. But in Portland, they were focusing on getting people back to downtown and out of their cars."

"We were a little naive about what we were doing," Gisvold said. "Maybe that's why it turned out so well."

In the late 1960s and early 1970s, America's cities were dying. Court-ordered school integration and the nation's love affair with the car sent white, affluent families hustling for the suburbs, newly reachable thanks to the federal highway system.

Portland's downtown population had dropped by 20 percent in the preceding decade, and almost two-thirds of the housing stock in the central city had been razed since the end of World War II in favor of urban renewal projects such as Interstate 405.

The Lloyd Center, barely a decade old, had siphoned shoppers away from downtown. Another new mall under construction in Tigard, Washington Square, threatened more damage.

"You could fire a cannon down any street in the central city after 5 p.m. and not hit anyone," Gisvold said.

The hot theory of urban development was that to survive, cities must make their downtowns as car-friendly as possible. In 1969, a Tacoma developer sought permission to replace the two-story parking deck across from Meier & Frank with a 12-story version. Department store executives bought wholeheartedly into the notion that women would accept no more than a one-block walk between their car and the hosiery counter. More parking, they figured, would be good for business.

But the project faced two obstacles: Nationally, the new Environmental Protection Agency was cracking down on air pollution. Locally, architects and historians argued that this particular block -- bounded by Southwest Morrison Street, Sixth Avenue, Yamhill Street, and Broadway -- had too much historic value to waste as yet another garage. Oregon's first public school once sat on the spot, as did Stanford White's grand old Portland Hotel.

So city leaders balked. Instead of approving the new garage, they agreed to study the availability and placement of parking downtown.

The study turned into something bigger, particularly after neighborhood activists and architects convinced the City Council to expand beyond a small, insular, politically connected committee of business leaders they initially selected.

"When you got more average citizens involved, they wanted to have a different kind of conversation," Gisvold said. "We wanted to talk about exactly what it meant to live and work in a city."

Their final report represented a new way of thinking about the world -- or at least downtown. Parking would be severely limited to short-term meters on the street and a few carefully placed long-term garages. The height of buildings would be capped, with zoning codes encouraging a "terracing" effect as people moved downhill from the retail core to the river. New office towers would be required to include stores and restaurants on the ground floor, a way to entice office workers out of their cubicles.

Denser development such as large office towers would be placed along two north-south transit corridors, namely Fifth and Sixth avenues. Smaller businesses would run along more pedestrian-friendly east-west streets, connecting shoppers and lunchtime strollers with the new park planned along the western bank of the Willamette River.

The overarching goal was to make downtown a place where people of all socioeconomic levels -- not just the "down and outers," as planning documents from the time refer to those on the lower end of the fiscal scale -- wanted to work, shop and live.

"The beauty of the 1972 plan is its simplicity," said Joe Zehnder, Portland's chief planner.

The 1972 document contains at least the first glimmers of the Pearl District, South Waterfront, Saturday Market, the streetcar, the Eastbank Esplanade and, on the spot where that 12-story garage was supposed to go, Pioneer Courthouse Square.

"What's amazing about that plan is how well it's lasted," said Troy Doss, a senior planner with the city. "If you go look at what they proposed, it's almost all been done."

Gisvold, 71, still bikes to work downtown from Irvington, now among the pricier bits of real estate in Portland. He's proud of what his group accomplished 40 years ago -- "A few very smart people got very rich because of what we did," he said a few weeks ago -- but also worries that the underlying principles his group came up with have faded with time.

City leaders are in the process of coming up with a new plan for the central city, to guide development through 2035. Planners and a citizens' advisory group, one larger and more politically connected that of Gisvold's team, will present their overarching concept to the City Council this week. Then they'll start the messier task of crafting specific policies, with final approval scheduled for 2014.

So far, the new plan contains few major surprises to anyone who has tracked the path of Portland development. "It's an expansion and an update, not a radical change," said Orloff, the historian who is leading the 2035 citizens' group.

The goal of a vibrant central city is the same, but the challenges are very different today.

"We're not competing with the suburbs anymore, but trying to figure out a way to complement what's happening in Hillsboro and Beaverton," Orloff said.

"It would be very simple to say, 'Let's just stick with what works. But it's time to have another conversation. What's the DNA of the city? What worked? What didn't? You have a large group of people who understand the challenge, who understand the foundation that has been built."

That might be the one distinct disadvantage Orloff and his team face compared to Gisvold's group: Unlike the planning pioneers of 1972, they know exactly what's at stake.